Method for fabricating prescribed flaws in the interior of metals

摘要

The method for fabricating a metal body having a flaw of predetermined size and shape located therein comprises placing half of the metal powder required to make the metal body in the die of a press and pressing it to create a flat upper surface thereon. A piece of copper foil is cut to the size and shape of the desired interior crack and placed on the upper surface of the powder and centered in position. The remaining powder is then placed in the die to cover the copper foil. The powder is first cold pressed and removed from the press. The powder metal piece is then sintered in a furnace at a temperature above the melting point of the copper and below the melting point of the metal. It is then removed from the furnace, cooled to room temperature, and placed back in the die and pressed further. This procedure results in an interior flaw or crack. Modified forms of the method involve using a press-sinter-press-sinter cycle with the first sinter being below the melting point of the copper and the second sinter being above the melting point of the copper and below the melting point of the metal.